Posts Tagged ‘Stefan Van Der Stigchel’

Some Serious Defects with How Attention Works

July 22, 2019

The subtitle to Dr. Stefan Van Der Stigchel’s book is “Finding Your Way in a World Full of Distraction.” This book discusses visual perception ignoring all the other senses. More importantly, it ignores cognitive processes such as thinking and solving problems, where attentional processes assume even greater importance.
The book is valuable in explaining the role not only that attention pays in vision, but also the need for information selection because perception is already overwhelmed. So the first problem is that the title over promises. It discusses only vision ignoring the majority of attentional processes.

Although Dr. Van Der Stigchel clearly is quite knowledgeable regarding attention and vision, he is woefully ignorant of important research in other areas. If only if he read the healthymemory blog post he would know of the research documenting the demands new technology is placing on our limited attentional process, and how that demand is degrading cognitive performance.

He makes the statement that he thinks that these concerns are ill-founded and even offers the suggestion, that he clearly pulled out of his keister, that he thinks the demands being placed on visual processing might actually improve performance in other areas of cognition.

There are two problems here. One is that he appears to be woefully ignorant of the relevant research in the area. The second is that it is professionally irresponsible to make statements in which one is ignorant regarding the relevant research.

There is also another problem that HM and his spouse regard as a shortcoming. They are disturbed about the number of people who cross the street failing to look to see if any cars are coming. The problem is not that drivers are homicidal, but there are limitations which should have been explained in this book. The driver’s attention can be distracted or the driver can be suffering information overload. This problem has significantly increased since the introduction of the smartphone. It is almost certain that pedestrian injuries and fatalities have increased, but HM has no data or anecdotes other than personal to report. But there have been accidents where passengers exiting a bus, crossing in front of the bus, but failing to note oncoming traffic. Deaths have resulted and drivers have suffered severe guilt from the accidents, even though the drivers are not at fault. This is the reason that drivers have to stop and not pass school busses when they have stopped for passengers. The assumption that all adults are too experienced to make this childhood mistake is wrong.

© Douglas Griffith and, 2019. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original conte

The Effects of Brain Damage

July 21, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” Visual neglect is a condition in which patients experience problems moving attention to the left or the right side of the visual world. Neglect usually results from damage to the right hemisphere of the brain. The attention regions in that part of the brain are responsible for moving attention to the left visual field. This condition has different levels of severity, and patients with the most severe form are completely unaware of what goes on in the neglected half of their world. When someone with this condition eats they eat only the food on the right-hand side of the plate. When they finish eating they believe that they have eaten everything because they have no access to the information on the other side of the plate. Only when his plate is turned around does the other half of his meal appear in the “intact” part of his visa world and does he realize that he hasn’’t finished his food after all. Neglect patients are actually able to move their attention, but only after receiving clear instructions and only for a short period of time.

Dr. Van Der Stigchel writes, “Around 25% of all patients with brain damage suffer from some form of neglect. Fortunately, it is usually a short-term problem. This is because there are all kinds of processes in the brain that are disrupted in the acute phase, but that are eventually able to return to normal. After a stroke, for example, excess blood has to be drained off from the brain. When that is done, many brain brain functions return to normal and the problem of neglect just vanishes. Even within only a few days of suffering brain damage, a patient may show no more signs of neglect. However, for some patients neglect remains a chronic condition, meaning that the problems they have with moving their attention are permanent.”

Cortical blindness is different from visual neglect and much more serious. Unlike neglect, cortical blindness is not an attentional deficit. There is no visual information in the blind field to which patients can move their attention. People suffering from cortical blindness cannot see any colors, shapes, or other visual building blocks in the affected field.

The Influence of the Past on Our Attention in the Present

July 20, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” We have excellent memory for the context in which objects are located. It appears that we are good at remembering visual context because the information involved is of the unconscious kind, something for which we have an apparently unlimited memory. But repeating a certain visual context is of no benefit to people who have trouble picking up unconscious information, like learning a new motor skill. This includes patients with Parkinson’s disease who are unable to learn new unconscious motor skills as a result of problem with the basal ganglia. But, when unconscious memory is still intact, as it is in the case of patients with Korsakoff’s syndrome, experiments show that contextual cueing continues to function normally. As it is conscious memory that is affected in these patients, they will probably be unable to remember what they ate for breakfast, but will still be able to react more quickly to a repeated search from the day before.

Regardless of their lack of conscious memory, the fact that Korsakoff’s patients still possess a well-functioning unconscious memory for visual context means that it can be used to learn new tasks. However, it is important that the information is acquired in a completely errorless manner. Otherwise, the patients will also take the errors on board unconsciously resulting in the inability to distinguish between correct and an erroneous one. It is unfortunate when it is assumed that patients who have no conscious memory or are unable to learn new skills.

Recently it has been found that it is possible for these people to acquire new skills when they use “errorless learning.” A team of scientists led by Erik Oudman studied the errorless learning of a specific skill—how to operate a washing machine. This requires the ability to interact successfully with the external visual world by pushing the right button at the right time. Korsakoff patients who had never operated a washing machine before were able to do so after a few errorless learning sessions. They were not able to explain how they did it, because the required actions were not stored in their conscious memory.

Memories influence our choice of where to move our attention. Magicians take advantage of this. Magicians look away from the spot where a change is about to take place, click their fingers to distract our attention, and toward our expectation by allowing changes to occur where we least expect them. The fact that we know they are making fools of us makes it all the more impressive and in no way diminishes the effectiveness of their tricks. A trick only fails to work when we know exactly what to look out for. In that case we focus our attention on the right spot, which allows us to see the change (HM has never been able to do this). It is a myth that magicians’ tricks are all about speed and that objects disappear too fast for us to be able to notice. Although speed is important, we humans are unable to make something disappear so fast that other humans will not notice, provided they are paying attention. The trick lies in distracting our attention.

Dr. Stefan Van Der Stigchel writes, “It is fascinating to see tricks that have been around for hundreds of years still being used in modern scientific experimental studies. One such experiment involved studying the eye movements of an audience watching a magician perform a trick in which he makes a cigarette “disappear” by letting it fall under a table while concentrating his gaze on and clicking his fingers. The results were very similar to the results of attention blindness experiments. The test subjects who failed to see the cigarette disappearing had seen the change with their own eyes but had not paid any attention to it.”

Another good example is the trick with the disappearing ball. The magician throws a ball into the air a couple of times and it just seems to vanish suddenly in midthrow. On the final throw the magician makes it appear as if he has thrown the ball when in actual fact he still as it in his hand. He follows the expected path of the ball with his head and eyes. The audience thinks he has thrown the ball and that it just vanishes into thin air. It is obvious that the audiences’ eyes are looking at the right spot, but that their attention has moved to the expected location of the ball on the basis of the direction of the throw and where the magician is looking.


July 19, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” In searching for something we try to take advantage of what is available in the environment. Something that is unique about the target that we are searching for can make that target pop-out. For example, if we are looking for something that is red and the environment is full of red objects that target will not pop-out. However, if it is the only red target, or if the majority of the objects in the environment are not red, then its redness will make that target pop-out.
Pop-out searching is also called parallel searching. Reaction time is not affected by the number of distractors (non-red targets) in the scene.

Say you are looking for a particular letter in a scene containing many letters. This is termed serial searching. In contrast to pop-out searching, which is an automatic process, serial searching is a conscious process. The reaction time for a serial search will be a function of the number of non-target objects in the scene. These non-target objects are distractors and search time is an increasing function of the number of distractors.

To determine whether a pop-out draws our attention automatically or not, we need to know what happens when the unique object is a distractor and not a target. Test participants were asked to find the anomalous shape among a group of other shapes. All of the shapes in the experiments are white. Half of the searches contain one unique distractor, which in this case is a gray circle. This distractor has the same shape as the other distractors, but it also has a unique color that distinguished it from all the other shapes on the screen, including that of the target object. We process information related to color faster than information related to shape because color is a stronger builder block than shape. In this case the distractor with the anomalous color is stronger that the object with the unique shape. If the unique distractor is not present, the unique shape of the target object results in a pop-out effect, meaning that the shape is able to grab attention quite easily. But it will take much longer to complete the search when the unique color is also present, even though there is no need to look for it. But we cannot escape its presence, not even when we know in advance which color will be doing the distracting. In fact, we will not be able to ignore the distracting color even if the search is repeated for hours on end. Unique color information is so strong that it will always draw our attention.

Making something suddenly appear is the best way to capture a person’s attention. Nothing activates our attention more strongly than a new object. It makes sense that we have evolved in this way. Objects that appear abruptly can represent possible danger. And the sudden disappearance of an object can also be a good reason for focusing attention on it.

How Your Eyes Betray Your Thoughts

July 18, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” Although we have two eyes, we are only able to fixate our gaze on one point in space at a time. The continuous movement of the eyes presents our visual system with interesting problems. If we were to see the actual images that fall on our retina, they would appear fuzzy and shaky because of the movements that the eyes make. Each individual eye movement is responsible for a separate part of the visual world falling on the retina. Yet we do not experience our visual world as a series of continuously shifting images, but rather as constant and fluid. We never become disoriented as a result of moving our eyes.

There is a difference between a retinal representation (the image that falls on the retina) and a spatiotopic representation (where the object is located in relation to our body). When we move our eyes to a different spot in space, the image that falls on our retina changes, but the world around us remains stable.

A similar updating process occurs in the case of memory. In order to know where we have already searched when we are looking for something, we need to remember those locations. When searching multiple locations the memory task become onerous. So it is useful to add some structure to our searching. If we always search our bookcase in the same manner there is no memory task and a strategy that guarantees search coverage. Searching in a haphazard is both inefficient and error prone as we are never able to recall all the individual locations that we have already searched.

There is an important difference between attention and eye movements. People are capable of shifting their attention without making any eye movements. This is useful when we find ourself talking to someone at a party but are actually more interested in someone else across the room. We are capable of looking our conversation partner in the eye while at the same time focusing our attention on the other person. The regions in our brain that are responsible for attention and eye movements overlap to a significant degree, and shifts in attention and eye movements co-occur in many situations. But we cannot make an eye movement without our attention first going to the end point of that movement. Attention precedes eye movements.

It is very important that our eye movements are made in the right direction to perform a task efficiently. Experts are good at developing strategies for their work, but they are often unaware of how they do what they do. This is similar to riding a bicycle: it is almost impossible to explain to a child how to ride a bike, because it doesn’t involve conscious competencies. But one can study how experts in different areas do their scanning.

It is very effective to show students what an expert looks at when he or she is scrutinizing a scan. This is true not only for radiologists, but also for all kinds of people who perform complicated tasks where looking at the right places is requires. Consider inspecting an airplane for mechanical faults before it departs on the next flight. Part of this job involves a visual check of the exterior of the airplane. When students are shown a view in which the most effective eye movements are projected on the screen, they learn faster and more effectively how to perform this kind of inspection. Eye-trackers are used to capture the performance of experts.

Change Blindness

July 17, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” Change blindness is the failure to spot a major change because something draws one’s attention away from the spot where the change is taking place. Inaccurate eyewitness accounts are often at the root of wrongful convictions, and these are sometimes caused by change blindness. Experiments have shown that test subjects often wrongly identify a person as a thief after seeing a video of a burglary simply because that person happened to appear in the clip. Consider this scenario: you see person 1 walk into a store and disappear behind a stack of boxes. When person 2 appears from behind the books and steals something the shop, Person 1 is identified as a thief.

There is an experiment regarding change blindness that has been recorded and you might already have seen it. In this experiment test subjects are asked to go to a counter and pick up a form. The person behind the counter bends down to get the form and disappears from view for a moment. Then a different person stands up in their place and hands the form to the test subject. Seventy-five% of the test subjects failed to notice the switch. Dr. Van Der Stigchel writes, “So don’t feel too bad the next time your sweetheart walks into the room and says to you, ‘Well, What do you think?’ and you have absolutely no idea which change in his or her appearance is being referred to.” HM’s advance is to respond, “You look great!” in these situations.

Dr. Van Der Stigchel writes that other change blindness rules appear to apply to moviemaking. Changes are less noticeable when they occur simultaneously with a major visual event, such as an explosion, just like a white screen that when shown very briefly can prevent test participants from noticing differences between two seemingly identical images.

Another trick of moviemakers is to use the actor’s direction of view. So when an actor is looking at a relevant object that is located off camera, most viewers will be so busy trying to figure out why the actor is looking at that they will fail to notice when a change occurs in the scene, such as a car driving into the shot. This also makes it easy to switch between two actors who are looking at and talking to each other. Viewers like to follow the direction of view of the person who is the focus of attention, because they assume that theirs is the most interesting point of view.

So we, in addition to radiologists, security scanners and movie directors, have to deal with the fact that we only ever have access to that small part of the world upon which we focus our attention.

Screening Performance

July 16, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” Radiologists have a difficult task when screening for breast cancer. Studies in the Netherlands have shown that the initial screening procedure has a detection probability of about 70%. So radiologists fail to detect incidences of cancer in over one quarter of all women who do in fact have breast cancer. These radiologists are not incompetent; they have a very difficult cancer to detect.

There is also the problem of falsely detecting a cancerous tumor. Additional examinations are very painful, and reacting to every minimal sign would lead to a lot of unnecessary discomfort. The chances of detecting a tumor on the basis of a minimal sign are known to be very low. But when scans in which a tumor was missed are checked again, the tumor usually turns out to be visible. The radiologist now knows that the scan does in fact contain a tumor and there is a maximum probability of actually finding it.

Scans are also done at airports for checking hand luggage. Security scanner operators spend hours every day searching the contents of bags and suitcases. Of course, the education and training of these airport security scanners is much less than that of radiologists. And the chance of finding dangerous content in these bags is much lower than the chance of correctly detecting dangerous objects in luggage. So fake explosives are placed in luggage for purposes of training and assessment. There are reports that operators fail to spot up to 75% of the fake explosives that are hidden in bags for test purposes.

An Americans study in to the performance of airport security personnel revealed that having to scrutinize scans on a daily basis helps them to be more precise when carrying out other unrelated search work. Out of a group of test subjects who were asked to find a well-hidden object on a computer screen, 82% were successful. A group of professional security scanner operators scored 88% for the same test although they did take longer to complete the task compared to nonprofessionals.

If you would like to check your prowess as a security scanner operator you can down load Airport Scanner, a free app ( that allows people to play
the task of finding dangerous items in luggage scans. This app has been a huge success worldwide and has millions of users. This app is partly funded by the American government, which is pleased with the amazing amount of information they are able to glean from the game. Researchers are also involved in the development of the game, and the first scientific articles were recently published containing the data retrieved from one billion searches. Some players have become so addicted that they have already competed thousands of searches. And this has provided developers with the opportunity to insert certain objects, only at sporadic intervals (in less than 0.15% of the searches). Dr. Van Der Stigchel notes that this research could not be done in a laboratory because the research subjects would end up running screaming from the lab after being subjected to hours and hours of tests. Based on a probability of 0.1%, an object will appear once every 1,000 searches, and in order to reach any firm conclusions about a player’s performance when attempting to find an extremely are object, 20,000 searches would need to be conducted. These data are now available thanks to the Airport Scanner app, and it has proven beyond doubt that players/professionals frequently fail to spot these rare, hidden objects.


July 15, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” This term, “infobesity,” as been coined by the popular media, but it is increasingly being referred to as a clinical disease. The term is the brainchild of a “trend team” employed by a company specializing in identifying trends among young people. Although there is very little scientific literature on the subject, the fact is that doctors are treating more and more teenagers these days for problems associated with a lack of sleep.

Dr. Van Der Stigchel writes, “One of the factors contributing to this lack of sleep is our insatiable appetite for information that is presented to us on-screen.” Obviously this leads to problems with concentration. From the scientific studies that have been done, young people are extremely frequent multimedia users. On average 18-year-olds spend a total of 20 hours a day on various media. Obviously this can only be because different media are used simultaneously, which further exacerbates the damage. The vast majority of this multimedia use is of the visual kind. Functions that rely on the spoken word have been replaced by visual ones. Unfortunately voice mail is becoming a thing of the past because it takes too much time, and people prefer to send their messages screen-to-screen instead. Dr. Van Der Stigchel notes that we are using the telephone less and choosing more often to interact with others on-screen and not only through hearing their voice. If e-mail and WhatsApp relied on the spoken word, they would be less popular.

Dr. Van Der Stigchel writes, “Screens are so efficient at communicating information that we see them everywhere nowadays. The result is a titanic battle for our attention, We have already established that it only takes a quick glance at a limited amount of visual information to know what that information is. In a single moment, we choose the one piece of visual information that is most relevant to us from all the information swirling around us. We then process this one piece of information deeply enough to be able to establish its identity. All of the other information continues to blink away furiously, but it can only become relevant when we decide to look again.”

How does one deal with infobesity? We need to deal with infobesity the same manner in which we deal with obesity. We deal with obesity by selectively controlling and reducing our food input. We deal with infobesity by selectively controlling and reducing
our information input. Unless one is a professional on-call, a physician for instance, there is no reason for staying continually connected. This FOMO (Fear of Missing Out) is irrational. Most, if not practically all, messages can wait until we have time to pay attention to them. When we interrupt what we are doing to process a message, there are two sources of attentional loss. There is additional information to deal with at the same time, and there are also time and attentional costs involved in switching between sources of information and processing them

An examination of different sources of information can lead to deletions of certain sources. Some information is of little value, so these sources of information should be eliminated. Our attentional resources are extremely limited, so we need to spend them carefully.

In conclusion, deal with infobesity by going on an information diet, and processing only those sources of information that have substantial value.

© Douglas Griffith and, 2019. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

So Then, How Good is the Human Visual System?

July 14, 2019

The simplest way to answer this question is to ask how frequently is the human visual system relied upon. Stefan Van Der Stigchel writes in his book “How Attention Works: Finding Your Way in a World Full of Distraction,” “When it comes to the transfer of information, the visual system is our single most important sensory tool. It takes a lot longer to convey the same information orally through speech than visually with the aid of symbols. This is because the visual system is able to process information in the blink of an eye. If you show someone a very detailed photo for just a second or two, they will still be able to describe the image to you fairly accurately afterward.”

In the 1970s Mary Potter conducted a series of experiments that clearly demonstrated this ability to rapidly process visual information. Research participants were given a written description of a scene (for example, “traffic on a street”) and then asked to find that scene among a series of images presented to them in quick succession. They were instructed to press a button as soon as they had identified the scene that identified the written description. No visual information regarding the scene was provided, neither the color of the cars nor the layout of the street. When the presentation rate was eight scenes per second, there was a success rate of 60% when it came to finding the scene that had been described in writing. This means that each image was visible for just 125 milliseconds, and the participants had to process all of the visual information in each scene within this extremely short space of time. A second study in which the participants only had to describe which scenes they had seen after the event only 11% of them were able to describe the scenes in any detail. Although they could say which scenes they had been shown, they were unable to provide any specific information about the content.

The difference in the results of these studies reveals distinct stages of information processing. All of the visual information that falls on the retina is registered in the brain. This information includes the colors and shapes of the world around us, and is processed in the primary visual cortex. At this stage we are still unable to identify individual objects. “Seeing” describes everything that falls as light on the retina. Although we “see” a lot of stuff, we only process a small amount of information deeply enough to know what that stuff actually is. Identification, knowing whether something is a tree or a green building, requires more in-depth processing and access to the identity of the object.

If we want to communicate a visual message, such as the information in a traffic sign, it is important to know what kind of information we can communicate in an instant. Although visual information can be communicated very quickly, there are limits. We are unable to process full sentences in a blink of an eye. Symbols, assuming the meaning of the symbol is known, are much more effective in this respect. Of course, it is impossible to devise a symbol for every piece of information, but when a road has multiple complicated signs, it can be to the detriment of both the message being communicated, and the intended recipients of the information, that is, the road users.

The communication of information is regarded as being successful when the relevant information reaches the intended user. Regardless of how impressed we might be by a particular advertisement, if we do not remember the intended message after being the advert (the name of the product), then the advertisement will not have worked and the attention architect will have failed in his or her task. HM remembers many advertisements, yet being unable to remember the name of the product. Perhaps HM has suffered brain damage, and is an atypical subject. Yet he is able to write a blog, so readers can reserve judgment. There are other advertisements, which he remembers but dislikes and is not prone to purchase the product. HM would very much like to review research on advertisements and how their effectiveness is evaluated.

© Douglas Griffith and, 2019. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

Is the Human Visual System Inefficient and Flawed?

July 13, 2019

This post is based on a book by Stefan Van Der Stigchel titled “How Attention Works: Finding Your Way in a World Full of Distraction.” The immediately preceding post might have you thinking that the human visual system is both inefficient and flawed. The fact that we cannot register what we see in our visual world suggests that the human visual system is a flawed one. Indeed, it will fail to detect a gorilla walking into a scene!

Before reaching this conclusion remind yourself that our species has managed to survive and prosper in a hostile environment. It is usually the case that the world around us is a stable and consistent one, and our brains work on this assumption. What is important is gathering information that is relevant to us. That’s what we need to focus on. We can ignore all the stuff that is of no value to us. A system that tried to process every scrap of visual information would be cumbersome and inefficient, and there is no need to process all the information available to us.

Dr. Van Der Stigchel writes “the system that uses less energy has an advantage in the evolutionary scheme of things. An efficient system makes the energy it does not use available to the system, and that is what our visual system also does. Although the retina catches the light from everywhere around us, only that information which is relevant to us is processed.”

Suppose when we went shopping in a supermarket we processed all the information we saw. Although we would know the brand and price of every product, that would cost us far too much energy.

Our visual system possesses a unique feature that allows it to present information very selectively: our continuous access to the visual world. All of the visual information that is available to us at any given moment is 100% accessible. All we need to do is to open our eyes and the information floods in. We can use the visual world as a kind of external hard drive. We do not need to store every single detail related to the external world in our internal world because all of the visual information is continuously available to us externally.

We only need to be able to recall internally to interact effectively with the external visual world where the relevant information is located in relation to our own location at any given moment.

Dr. Van Stigchel asks us to imagine the following: “we and a friend are walking down a busy street in town on our way to a coffee bar at the end of the street. There are people everywhere and neon signs flashing all around, At that moment, only certain aspects of the visual world are relevant to us: the coffee shop in the distance and our friends walking beside us. We are moving, so all of the information is moving too relative to our position. We use our eyes to access the visual world around us and note only the location of the information that is relevant to us. We would notice if the coffee bar suddenly disappears, our friend runs off, or if a screaming gorilla approaches because this information is relevant to us. We can afford to ignore everything else.”